So far, for example, Patent Document 1 discloses a failure detecting device for an internal combustion engine that includes electromagnetically-driven type intake and exhaust valves. The conventional failure detecting device detects a failure of the intake and exhaust valves at the time of normal operation of the internal combustion engine in which the opening and closing of the intake and exhaust valves are being performed. More specifically, the aforementioned failure detecting device determines whether or not there is a failure of the intake valve being opened on the basis of the width of a change in an intake pipe pressure at a predetermined crank angle period, and determines whether or not there is a failure of the intake valve at a closed state or a failure of the exhaust valve being opened or closed, on the basis of the width of a change in an average value of the intake pipe pressure among cylinders.
Including the above described document, the applicant is aware of the following documents as related art of the present invention.